Object-Oriented Programming (OOP)

What is Object-Oriented Programming (OOP)?

Object-oriented programming (OOP) is a style of programming that uses modular components to build large, complex software applications.

Key Takeaways

Object-oriented programming can have a high learning curve.
OOP builds software around classes that represent real-world entities or concepts.
Classes act as templates that allow developers to create modular units of code called objects.
Each object contains data and specifies the operations that can manipulate the data.
Software applications that are designed with OOP principles typically conduct operations on objects to ensure data integrity and consistency.

How OOP Works

OOP developers build software by using templates called classes. Classes are designed to structure code in self-contained modular units called objects. Each class defines what kind of data an object can hold and what actions the object can perform.

The principles of encapsulation and abstraction allow object instances to be repurposed and reused. Encapsulation bundles data and actions together to create an object. Abstraction hides the object’s inner workings and provides an interface that allows objects to interact by sending messages.

The principles of inheritance and polymorphism allow classes to be modified so they can be used for different purposes. Essentially, inheritance allows developers to create new classes that are based on existing classes, and polymorphism allows objects of different classes to be treated as if they belong to the same class.

OOP Concepts

OOP concepts are intended to be understood intuitively because they are modeled after real-world interactions, but the terminology can be confusing. The key is to find simple explanations for each concept. Hopefully, this OOP definition will help.

Here are some very simple explanations of terms you are likely to run into when reading about OOP or listening to a discussion that involves object-oriented programming:

Class is a template that defines the structure and behaviors of modular, self-contained units of code.
Objects are modular, self-contained units of code.
Instance is a specific object.
Attribute is data stored inside an object.
Method describes how an object can interact with other data or objects.
Constructor is a mechanism that ensures an object is in a valid state before it’s used.
Method call is an instruction that tells an object what task to perform.
Derived class is a new class based on an existing class.
Base class is the original class that provides common structure and behaviors to subclasses.
Subclass is a synonym for derived class.
Message passing is how objects communicate with each other.

Four Main Principles of OOP

The four main principles of OOP that support modular, reusable, and maintainable code are encapsulation, abstraction, inheritance, and polymorphism.

Here is a more technical explanation for each principle:

Encapsulation

Defines how attributes and methods are bundled together within an object. One key aspect of encapsulation is data hiding. By restricting direct access to an object’s attributes, the class forces any interaction with its data to be performed through its methods. This control mechanism protects the attributes from being accessed or modified directly and ensures that the object’s methods are consistent.

Abstraction

Simplifies complex code by focusing on essential features and deprecating details that aren’t essential. Abstract classes and interfaces define a contract that specifies methods an object needs to implement. The contract allows objects to interact at a high level without needing to know about each other’s inner workings.

Inheritance

Allows programmers to create a derived class that automatically includes all the attributes and methods of its base class and any modifications. Essentially, inheritance establishes an “is-a” relationship between the classes. This relationship allows programmers to write generic code that can work with objects of different classes as long as they share a common base class.

Polymorphism

Allows objects of different classes to be treated as if they are objects of a common superclass. This can be accomplished by overriding methods and using dynamic binding (also known as late binding). When an overridden method is called on a derived class object, the derived class’s implementation is executed instead of the base class’s implementation. This allows developers to write code that works with related objects without having to duplicate code for each specific type.

Popular OOP Languages

Popular languages that support OOP include Java, Python, C++, C#, Ruby, JavaScript, TypeScript, PHP, and Swift.

Each language offers unique features that make it more suitable for certain types of applications or environments. The choice of programming language depends on the specific project requirements, platform compatibility, developer expertise, and the available ecosystem of software libraries and tools.

Object-Oriented Programming Examples

Salesforce CRM software is a well-known example of how OOP can be effectively used to build robust, customizable, and scalable enterprise applications. Salesforce CRM data is organized into objects whose attributes and interactions with other objects mirror real-world relationships.

SAP has used OOP principles to support legacy software. SAP’s primary programming language is ABAP (Advanced Business Application Programming). Arguably, ABAP was not specifically designed for OOP, but ABAP Objects made it very clear that SAP developers value OOP concepts.

OOP Pros and Cons

Object-oriented programming offers powerful modeling tools and methodologies, but it also comes with its own set of challenges, especially as projects grow in complexity.

Pros

Improved code organization and readability
Easier maintenance and debugging
Increased code reuse and reduced redundancy
More accurate modeling of complex systems
Support for collaborative development

Cons

High learning curve
Requires careful planning
Risk of creating unnecessary classes and objects
Misuse of inheritance can complicate development
Debugging is challenging when behaviors are distributed across classes

The Bottom Line

If you are considering using OOP, it can be useful to consider object-oriented programming’s meaning and implications in the context of a specific project and programming language. An OOP approach is useful for managing large enterprise-level projects that will be improved iteratively over a number of years, but it can be overkill for small development projects with tight deadlines.